UNS NO8904, generally known as 904L stainless steel, is a low carbon austenitic nickel-chromium stainless steel with increments of molybdenum and copper. 904L pipe fittings and 904L product structures are principally utilized where the erosion safe properties of 316L and 317L are deficient, particularly in extreme destructive conditions.

In Most Environments 904L Stainless Steel has an erosion execution middle between the standard & austenitic evaluation 316L and the exceptionally alloyed 6 Mo and comparable super austenitic evaluation.

Albeit initially produced for its imperviousness to sulphuric corrosive it additionally has a high imperviousness to an extensive variety of situations. A PRE of 35 shows that the material has great imperviousness to warm ocean water and other high chloride situations. High nickel substance brings about a vastly improved imperviousness to stretch erosion breaking than the standard austenitic evaluations. Copper adds imperviousness to sulphuric and other decreasing acids, especially in the extremely forceful "mid focus" range.

In many situations SS 904L has a consumption execution middle of the road between the standard austenitic level SS 316L and the much alloyed 6% molybdenum and comparable "super austenitic" levels.

In forceful nitric corrosive SS 904L has less resistance than without molybdenum evaluations, for example, SS 304L and SS 310L.

For greatest anxiety erosion breaking resistance in basic situations the steel ought to be arrangement treated after chilly work.

Good resistance to oxidation, Great imperviousness to oxidation, however like other exceedingly alloyed evaluations experiences structural insecurity (precipitation of fragile stages, for example, sigma) at raised temperatures. 904L ought not to be utilized above around 400°C. Annealing heat to 1090-1175°C and cool rapidly. Susceptible to hot cracking in constrained weld elements. It has high purity, low sulphur grade.